Cook posted a video on his Instagram account Thursday of a tearful Cuoco flashing a diamond ring on her finger and shouting "we're engaged" before officially accepting Cook's proposal with a loud "yes." Thursday also happened to be Cuoco's 32nd birthday.The 26-year-old Cook said in the caption of the video that the engagement comes after nearly two years of dating. He added: "This is the best night of my life and I think the video shows it is the best night for kaley as well."Cook is a professional equestrian and the son of Intuit co-founder Scott Cook. Cuoco has starred as Penny on "The Big Bang Theory" since the sitcom's debut in 2007.